Breeding OA-resistant oysters

Crossbreeding and Selection for Resistance to Ocean Acidification in Pacific Oysters

Researchers will use genetic approaches to develop broodstocks for the shellfish industry that are better adapted to increasingly corrosive seawater impacting our coasts and estuaries.

Principal Investigator

Jonathan Davis, Pacific Shellfish Institute and Taylor Shellfish Company, Inc.

Co-Principal Investigator

Brett Dumbauld, USDA Agricultural Research Service

Carolyn S. Friedman, University of Washington, School of Aquatic and Fishery Sciences

Steven Roberts, University of Washington, School of Aquatic and Fishery Sciences


High-CO2, low-pH marine conditions have devastated valuable Pacific oyster hatchery crops. This project will breed oysters for resistance to ocean acidification using a large number of genetically distinct lines maintained by a commercial grower. The oysters will be conditioned in ambient and elevated dissolved-CO2 levels at two critical larval stages to determine whether, and in which genetic lines, exposure induces changes in gene expression. High-, medium- and low-performing lines will then be field tested at four farms. The trials will greatly expand ongoing investigations of the intergenerational effects of exposing breeding adult oysters to acidified waters.

Research Updates

Washington Sea Grant-supported researchers teamed with industry partners to produce lines of Pacific oysters through a comprehensive breeding process that focused on testing OA responses in early- and late-development larvae. They successfully produced 42 lines of hybrid Pacific oysters by crossing genetically distinct inbred lines at two Washington locations. The team also began field testing previously screened, surviving hybrid lines to evaluate their potential for commercial production. In related testing, researchers assessed how embryo and juvenile-stage Pacific oysters responded to different levels of OA using the 42 oyster lines generated from crossbreeding. After several months of growth, they then evaluated survival of the experimental groups’ seed.

Initial analyses indicated several lines with high breeding potential for hybrid commercial production. To better measure response to different OA conditions, investigators developed an enhanced, more reliable apparatus for assessing response of oyster embryos and late-stage larvae to low pH conditions. The improved apparatus allowed flow-through seawater control that enabled cultured microalgae to be added without changing water chemistry.